Colin Beattie MSP and Councillor Colin Cassidy have been alerted to an oil spillage at Newbattle Storm Water Works by a member of the public.
At the site they saw the spillage extending to the bottom of the track just off Newbattle road.
They were shocked to find a large amount of car parts, engine oil, tyres and documents had been dumped. The containers holding the engine oil had leaked badly and spilled across a wide area.
Police Scotland, Scottish Environment Protection Agency (SEPA) and Scottish Water were notified, and the MSP and councillor are pressing for a clean-up to begin.
Mr Beattie (SNP) said: “It is absolutely appalling that someone has decided to dump this rubbish and to apparently deliberately allow the oil spill to potentially enter the water system.
“I would like to thank the member of the public for alerting myself and Councillor Cassidy to the issue and I hope that the clean-up begins soon.”
Councillor Cassidy (SNP) said: “For anyone in this day in age to do this to the environment and cause so much damage is beyond words. I thank all the authorities involved for their co-operation.”
A spokesman for SEPA said: “We attended the site on April 2. We assessed that no run-off was entering the watercourse, which is the Ochre Burn, and will continue to monitor this going forward.
“We have been liaising with Midlothian Council and are aware they have been working with the landowner to contain, investigate and secure clean-up.”